1. Field of the Invention
The present invention relates to a method for testing mentation of humans, and a mentation test apparatus. More specifically, the present invention relates to a highly reproducible and reliable mentation test method that is able to sensitively test human mentation without being affected by intelligence, educational carrier and the effects of repeated learning, and a mentation test apparatus.
2. Description of the Background Art
A mentation test method called TMT (Trail-Making-Test) has been used for finding diseases such as cerebrovascular disorder, schizophrenia and dementia. In this method, test subjects are given a task to sequentially line the figures of 1 to 25 randomly distributed on a sheet of A4 paper within a period as short as possible in a manner similar to one stroke drawing. While the time required for a test subject to complete the task, or to gain a score, is recognized to be affected by the intelligence quotient of the subject as well as by aging to some extent, there are different opinions on the effect of the school carrier.
Since the task can be achieved within a short period of time by simultaneously proceeding two sorts of tasks of search of a target and memory of locations of letters and figures other than the target in the TMT method, higher concurrent processing ability between recognition and retention of information (memory), or higher processing ability of the working memory, results in better results.
However, many other functions such as flexibility of mentation, attention span (fatigue), visual search ability and motor ability are required besides the working memory for achieving the task of the TMT method. Accordingly, lower performance of the aged person is conjectured as a result of age-related changes of these factors above.
However, it is impossible in the currently available TMT method to analyze what factors have affected to what extent on the decrease of the score, thereby making it impossible to assess the working memory ability of aged persons and dementia patients.
Accordingly, one object of the present invention for solving the problems in the conventional art is to provide a mentation test method capable of testing human mentation such as conjecture of brain mentation age, discrimination of initial dementia and prediction of onset thereof as well as diagnosis of onset prediction probability and screening of mentation of the senile dementia patients, decision of the rehabilitation effect on the aftereffects of the cerebrovascular dysfunction, therapeutic effects of medicines and investigation of side effects such as sleepiness, testing of intoxication, testing of peripheral attention visual field, testing of the cerebral dominant hemisphere, testing of various neuropathy and mental disorder such as schizophrenia and cerebrovascular disorder (symptoms and diagnosis, and decision of the effect of rehabilitation and treatment), and check of mental fatigue. Another object of the present invention is to provide a mentation test apparatus capable of executing the method described above.
The mentation test method according to the present invention (referred as a method according to the present invention hereinafter) for attaining the foregoing objects uses a technical method comprising displaying a given number of randomly disposed targets to be pointed in a prescribed order on a screen of a display device, measuring a search response time required for a test subject to search each target by pointing the target in a prescribed order, and calculating the test subject""s mentation based on the measured values.
In a method according to the present invention, many normal test subjects are given a visual search task for pointing the targets displayed on the screen of the display device in a prescribed order to measure the search response time for each target. Consequently, the correlation between the age and score can be statistically determined, and brain""s mentation age can be conjectured from the statistically determined correlation and score of each test subject.
In a different method according to the present invention, a test subject is given a task in which mnemonic ability of the test subject is reflected on reduction of the search response time, and a task in which mnemonic ability of the test subject is hardly reflected on reduction of the search response time to measure the search response time for each target. Consequently, more accurate correlation between the age and score can be statistically determined, and the brain""s mentation age can be more accurately conjectured from the statistically determined correlation and score of each test subject.
In a different method according to the present invention, the test subject is given a task in which mnemonic ability of the test subject is reflected on reduction of the search response time, and a task in which mnemonic ability of the test subject is hardly reflected on reduction of the search response time to measure the search response time for each target. Consequently, processing ability of the working memory can be analyzed by calculating contraction rate of the search response time arising from the working memory.
Prediction probability of early onset of dementia or onset of dementia can be diagnosed by statistically determining the contraction rate of the search response time arising from the working memory of the normal subjects and dementia patients, and by comparing the statistically determined contraction rate of the search response time arising from the working memory with that of each test subject.
When the test subject is given a task in which mnemonic ability of the test subject is hardly reflected on reduction of the search response time in the method according to the present invention, and when the search response time is measured for each target, then the search response time for the late turns of search tends to be prolonged, besides it is further elongated as the test subject is aged.
Delay of this search time is thought to arise from fatigues, and the causes of the fatigues include intoxication, effects of medicines, side effects of medicines, asthenopia and mental fatigue.
Therefore, the correlation between the cause and achievement is statistically determined using, for example, age as a parameter for every causes or for every time when two or more of these causes compete to one another in the present invention. It is then made possible to diagnose the extents of intoxication, effects of medicines, side effects of medicines, asthenopia and mental fatigue by comparing the correlation with the score of each test subject.
The other causes of arising delay of the search response include constriction of peripheral attention visual field and loss of exercise function. The extents of constriction of peripheral attention visual field and loss of exercise function can be also diagnosed by collecting statistical data by the same method as described above, and by comparing the statistical data with the test score of each test subject.
The method according to the present invention will be described in more detail hereinafter.
While the display device comprising a screen for displaying targets is not particularly restricted so long as the display device is able to switch the display image on the screen for every responses of the test subject, it is preferable that the display device can quickly switch the screen and is excellent in the degree of freedom for setting image contents.
For example, a display device like a paper picture show may be employed, whereby the device comprises a roll paper for sequentially and continuously printing the images that change for every response of the test subject, and the roll paper is wound from one end to the other end for every screen when the test subject show a correct response. However, it is preferable to use a display device that can display the targets on the screen by electronic control that can rapidly switch the screen and is excellent in the degree of freedom in setting the contents of the images, or a display device that can display the targets on the screen by computer control.
Although the number of the targets to be displayed is limited on a sheet of paper, the computer controlled display method is able to be infinitely continued by erasing the pointed targets from the screen and creating new targets. Since the response time is gradually delayed by proceeding the search responses for pushing the points, analysis of readily occurring fatigue is possible from the degree of delay of the response time. It has been already shown that response delay phenomenon is observed at an earlier time in the patients with chronic fatigue syndrome than in normal subjects, which enables the patients with chronic fatigue syndrome to be discriminated.
The representative display device of this sort includes a cathode ray tube (CRT) display device, a liquid crystal display device and a dichromic mirror display device.
Usually, a display device available has target pointing means comprising a cursor displayed on the screen, a cursor control means for controlling the display position of the cursor in accordance with operations by the test subject, and a pointer for allowing the computer to recognize that the cursor has been positioned at the position of the target by the input operation of the test subject.
However, it is preferable that a touch panel comprising a transparent matrix switch is overlaid on the display screen so that the corresponding target is pointed when the test subject presses the position corresponding to the target on the touch panel overlaid on the screen, in order to avoid large errors from occurring as a result of the skill and delay for operating the cursor and pointer by the test object.
While the targets pressed by the test subject in a correct order may be left behind on the screen in the method according to the present invention, it is preferable that the targets pointed in a correct order are erased from the screen in order to avoid misunderstanding of the pointing order and repeatedly pressing the same target.
However, the conditions for searching the targets turn out to be easier at the later order of search when the number of the targets displayed on the screen decreases by erasing the pointed targets. Consequently, the target may be so readily and promptly searched that delay due to fatigue is hardly detected.
Accordingly, dummy targets are displayed in place of the erased targets at random positions or at the position of the erased targets in the present invention, when the targets are pointed in a correct order. It is therefore desirable that the targets are searched under the same condition irrespective of the order of search, or under the conditions that the targets are searched in a correct order among the constant number of similar images displayed on the screen, in order to sharply reflect the delay of the search response time due to fatigue.
The targets as used herein is not restricted to the target to be immediately searched, but includes the targets to be searched and pointed sooner or later. The targets comprise images provided with marks representing the order of pointing, for example figures, alphabets or Japanese letters (katakana or hiragana), or images comprising the marks themselves indicating the order of pointing.
The dummy target comprises an image displayed by a similar configuration to each target, and is displayed at the position of the erased target, or at random positions. While the dummy target may have the same color, shape and size as those of the target, at least one of the color, shape and size of the dummy target may be different from those of the target for simplifying search of the target to some extent.
When the mark indicating the order of pointing is displayed as a target, or displayed in addition to the target, a mark other than the marks already displayed may be displayed as a dummy target, or may be displayed in addition to the dummy target, so that search operations are simplified to some extent. At least one of the color, shape and size of the target may be different from those of the dummy target, or a dummy target not attached with the mark may be displayed in place of the erased target and mark, when a mark indicating the order of pointing is displayed in addition to the target.
The display position for the target may be fixed in the present invention, or may be changed every time when the target has been pointed in a correct order. The display position for the dummy target may be also fixed, or may be changed every time when the target has been pointed in a correct order.
The search response time is contracted in descending order of search, by the parallel processing of search of a target and memory of the other targets and dummy targets, or by operating the working memory, when the display position of the target and dummy target are fixed.
The search response time is further contracted in descending order of search, particularly when at least one of the color, shape and size of the dummy target is different from those of the target for easy recognition of the decreased number of the targets.
When the display positions of a target, or the display positions of the target and a dummy target are changed every time when the target has been pointed in a correct order, on the contrary, the memory of the test subject is hardly reflected on contraction of the search response time since the memory on the target position before pointing the last target is invalid. Consequently, the search response time is prolonged by fatigue as the search order is descending.
While visual disorder such as presbyopia, cataract and glaucoma may result in delay of the search response time in the method according to the present invention, the effect of such delay can be solved by devising the size, shape and color of the target, and the background color.
It was proved in the course of development of the present invention that highly reliable calculation results are obtained by executing the test 1, test 2 and test 3 in a prescribed order, measuring the search response time required for searching the targets in each test for every targets, and calculating the mentation age of the test subject""s brain based on the measured values. The contents of the test 1, test 2 and test 3 are as follows:
The test 1 comprises the steps of displaying a given number of targets to be pointed in a prescribed order by randomly distributing them on the screen of a display device, allowing a test subject to point each target in a prescribed order, and displaying a dummy target having a different color from the target at the position of the pointed target in place of the pointed target when the target is pointed in a correct order;
The test 2 comprises the steps of displaying a given number of targets to be pointed in a prescribed order by randomly distributing them on the screen of a display device, allowing a test subject to point each target in a prescribed order, and displaying a dummy target at random positions in place of the pointed target when the target is pointed in a correct order; and
The test 3 comprises the steps of displaying a given number of targets to be pointed in a prescribed order by randomly distributing them on the screen of a display device, allowing a test subject to point each target in a prescribed order, and displaying a dummy target at random positions in place of the pointed target when the target is pointed in a correct order, besides changing the display positions of each target and dummy target.
The number of the targets displayed is not particularly restricted, but 25 targets may be initially displayed as in the conventional TMT method.
It is preferable to disregard the search response times corresponding to the targets from the first to a prescribed order, for example from the first to the fifth targets, in each test from the test data considering emotional tension and the effect of unaccustomed work at the beginning of the test.
With respect to the search response times for the targets thereafter, the targets are divided into two groups of the first half targets of sixth to 15th and last half targets of 16th to 25th in order to simplify the mentation test, and the mentation test is calculated based on the sum of the first half search response times and last half search response times.
The mentation age of the test subject""s brain is actually calculated based on the results of the first half of the test 1, the last half of the test 2, the first half of the test 3 and the last half of the test 3, because a strong correlation with the age has been observed among the first half of the test 1 as a sum of the search response times from the sixth to the 15th in the test 1, the last half of the test 2 as a sum of the search response times from the 16th to the 25th in the test 2, the first half of the test 3 as a sum of the search response times from the sixth to the 15th in the test 3, and the last half of the test 3 as a sum of the search response times from the 16th to the 25th in the test 3.
Equations (regression functions) are used for the stepwise regression analysis with a regression curve correction, which are represented by the following equations 1 and 2.
X=0.0154xc3x97(first half of task A)+0.00978xc3x97(last half of task C)xe2x88x920.005535xc3x97(first half of task C)+0.003645xc3x97(last half of task B)xe2x88x923.681(distinction of sex)xe2x88x926.612xe2x80x83xe2x80x83Equation 1
The xe2x80x9cdistinction of sexxe2x80x9d is substituted with 1 or 2 when the test subject is male or female, respectively.
xe2x80x83ATMT calculated age(Y)=xe2x88x920.0091X2+1.8771Xxe2x88x9219.192xe2x80x83xe2x80x83Equation 2
While the mentation age of the test subjects"" brain is somewhat distributed in their twenties, it is close to the actual age in their thirties or more, showing that this method is highly reliable.
The test subject may be informed of his (her) mentation state at the test site in the method according to the present invention, when the search response time in each test is displayed on the screen immediately after completing the entire tests. The test subject can enjoy the mentation test of the brain as if he (or her) is playing a game, because the test subject is able to learn his (her) mentation age of the brain at the test site when the calculated mentation age of the test subject""s brain is displayed on the screen after completing the entire tests.
It was also proved in the course of development of the method according to the present invention that presence of dementia or prediction probability of onset of dementia can be decided from the calculated values obtained by executing the test 2 and the test 3 in a prescribed order, measuring the search response time required for searching each target in each test, and calculating the ratio of the search response time in the test 3 against the search response time in the test 2.
It was proved that the ratio is 0.85 or more for the dementia patients while the ratio is less than 0.85 for most of the normal subjects, when the ratio of the search response time in the test 3 against the search response time in the test 2 (the contraction ratio) is calculated.
Accordingly, presence of early stage dementia can be diagnosed whether the ratio is 0.85 or more or not. When the ratio is less than 0.85, it is possible to diagnose prediction probability of onset of dementia by the calculation result or by the percentage obtained based on the calculation result.
When the result of the diagnosis, or the ratio of the search response time of the last half of the test 3 relative to the search response time of the last half of the test 2, is 0.85 or less, the test subject can be informed of the prediction probability of onset of dementia at the test site by displaying the ratio or the percentage calculated based on the ratio after completing the entire tests as the prediction probability of onset of dementia. When the search response time for each test is displayed on the screen after completing the entire tests, the test subject can also recognize his (her) mentation state at the test site.
Of course, the test results of various mentations may be printed out with a printer, expressed as a voice output, or recorded on an appropriate recording medium.
A simple task in which the targets are pointed in a order of xe2x80x9c1xe2x86x922xe2x86x923xe2x86x92 . . . xe2x80x9d, xe2x80x9cAxe2x86x92Bxe2x86x92Cxe2x86x92 . . . xe2x80x9d, and xe2x80x9caxe2x86x92bxe2x86x92Cxe2x86x92 . . . xe2x80x9d and xe2x80x9cxcex1xe2x86x92xcex2xe2x86x92xcex3xe2x86x92 . . . xe2x80x9d may be employed in the method according to the present invention. However, an optimum test tailored for the intelligence level of a test subject may be also possible by permitting the test subject to select a higher rank of task such as a combination of two or more sorts of orders (a category shift task) such as xe2x80x9c1xe2x86x92axe2x86x922xe2x86x92bxe2x86x923xe2x86x92c. . . xe2x80x9d or a inverse order distracter task such as xe2x80x9c25xe2x86x9224xe2x86x9223xe2x86x92-xe2x80x9d as in the TMT-B task.
Otherwise, emergence patterns and coordinates of the targets may be previously determined in the test 3 while displaying dummy targets every time at random positions, which enables cerebral dominant hemisphere and visual field disorders such as constriction of peripheral attention visual field to be tested from the previously stored coordinates of the targets (vectors) and their search response times.
The mentation test apparatus according to the present invention (referred as an apparatus according to the present invention hereinafter) for attaining the foregoing objects employs a technical method comprising: a display device for displaying images by electronic control; a transparent touch panel overlaid on the screen of the display device; an image control device for randomly displaying a given number of targets to be pointed in a prescribed order on the screen by electronic control of the display device, and for erasing the targets that have been pointed in a correct order when a test subject have pointed the targets by pressing the positions on the touch panel corresponding to each target in a prescribed order; a time counter for measuring the search response time required for the test subject to search the targets in a correct order and/or the search response time required for the test subject to search a given number of the targets in a continuous order; and a processing unit for calculating the test subject""s mentation based on the search response time measured with the time counter.
In the method described above, a given number of the targets to be pointed in a prescribed order are displayed on the screen by being randomly distributed, the search response time required for the test subject to search each target is measured by allowing the test subject to point each target in a prescribed order, and the mentation of the test subject is calculated based on the measured values.
Detailed description of the method according to the present invention is omitted herein in order to avoid repeated explanations, since the display device has been described in the section of the detailed description of the invention.
The touch panel comprises, as is known in the art, a matrix of a number of switching elements using a transparent electrode. The display positions are transferred into the image control device as coordinates when the switching element corresponding to each target on the screen is pressed.
The image control device is provided with a function for allowing a given number of the targets to display on the screen of the display device by randomly distributing them.
Actually, the image control device comprises, for example, a data base that stores an initial display panel table in which the coordinates of a given number of the targets displayed on the initially displayed screen (initial screen) are recorded, and a main unit for controlling the display device based on the read-out data from this data base and input data from the touch panel.
Consequently, the main unit reads the disposition (emergence pattern) of the targets and dummy targets displayed on the screen from the data base, and controls the display device to display the targets and dummy targets on the screen.
Although the display positions of the targets have been previously determined as coordinates in this emergence pattern, the display position of each target is actually determined so that each target is displayed at random positions on the screen.
The image control device is also provided with a function for halting display of the corresponding targets when the main unit reads a coordinate of a switching element pressed through the touch panel, and when the coordinate coincides with the coordinate of a correct target, and a function for erasing the corresponding target from the screen.
The image control device allows the display device to display the dummy target at the position of the erased target or at random positions in place of the erased target, in order to maintain the condition that the targets are searched in a correct order among a given number of resembling targets displayed on the screen.
The data with regard to the color, shape, size and display position of the dummy target may be stored, for example, in the data base.
When the image control device permits the display device to display a mark indicating the order of pointing as a target, the display device displays a mark other than the mark that has been already displayed at the position of the erased target or at random positions in place of the erased target, in order to prevent misunderstanding of the pointing order or repeated pressing.
When the figures of 1 to 25 are displayed as the targets, for example, the figure of xe2x80x9c26xe2x80x9d is displayed at the position where the figure xe2x80x9c1xe2x80x9d has been displayed or at random positions as a dummy target in place of the figure xe2x80x9c1xe2x80x9d when the figure xe2x80x9c1xe2x80x9d has been pointed and erased from the screen. Likewise, when the image control device allows the display device to display a mark indicating the order of pointing in addition to the target, the display device displays a dummy target together with a mark other than the mark that has been already displayed at the position of the erased target or at random positions in place of the erased target, in order to prevent misunderstanding of the pointing order or repeated pressing.
While an image comprising the same color, shape and size as those of the target may be used as the dummy target, the image control device may permit the display device to display a dummy target in which at least one of the color, shape and size is different from those of the erased target, thereby enabling the range of the search area of the remaining targets to be narrowed and the search response time to be contracted.
The data base may be made to store the emergence pattern of the targets before the targets are pointed and the emergence pattern of the remaining targets and dummy targets after each target has been pointed, besides making the display position of each target in each emergence pattern to be different to one another. As such, the image control device reads the emergence pattern of the remaining targets and dummy targets after the targets have been pointed every time when the targets have been pointed in a correct order, or allows the display device to display each target that has not been pointed yet and dummy target by changing their display positions.
When the image control device comprises a function for permitting the display device to display each target at a fixed position until all the targets have been sequentially pointed, a function for allowing the display device to display the remaining targets by changing their display position every time when a target has been pointed, and a selection unit for making any one of the functions effective, both tasks of the tests in which the target positions are fixed and the target positions are changed may be simultaneously executed.
For example, the tests available comprise the test 1 in which a given number of the targets to be pointed in a prescribed order are displayed on the screen of the display device by being randomly distributed, the test subject is requested to point each target in a prescribed order, and a dummy target having a different color from the pointed target is displayed at the position of the pointed target in place of the pointed target when the target has been pointed in a correct order; or the test 2 in which a given number of the targets to be pointed in a prescribed order are displayed on the screen of the display device by being randomly distributed, the test subject is requested to point each target in a prescribed order, and a dummy target is displayed at the position of the pointed target in place of the pointed target when the target has been pointed in a correct order; and the test 3 in which a given number of the targets to be pointed in a prescribed order are displayed on the screen of the display device by being randomly distributed, the test subject is requested to point each target in a prescribed order, and a dummy target is displayed at the position of the pointed target in place of the pointed target while changing the display positions of each target and dummy target when the target has been pointed in a correct order.
Three sorts of tests according to the functions below are available, when the method according to the present invention comprises a function for displaying the targets by fixing their positions until all the targets have been sequentially pointed, besides displaying a dummy target having a different color from the pointed target in place of the pointed target, a function for displaying the targets by fixing their positions until all the targets have been sequentially pointed, besides displaying a dummy target at random positions in place of the pointed target, a function for displaying the remaining targets by changing their positions every time when a target has been pointed, and a selection unit for making any one of the functions effective.
For example, the tests available comprise the test 1 in which a given number of the targets to be pointed in a prescribed order are displayed on the screen of the display device by being randomly distributed, the test subject is made to point each target in a prescribed order, and a dummy target having a different color from the pointed target is displayed at the position of the pointed target in place of the pointed target when the target has been pointed in a correct order; the test 2 in which a given number of the targets to be pointed in a prescribed order are displayed on the screen of the display device by being randomly distributed, the test subject is made to point each target in a prescribed order, and a dummy target is displayed at random positions in place of the pointed target when the target has been pointed in a correct order; and the test 3 in which a given number of the targets to be pointed in a prescribed order are displayed on the screen of the display device by being randomly distributed, the test subject is made to point each target in a prescribed order, and a dummy target is displayed at random positions in place of the pointed target while changing the display positions of each target and dummy target when the target has been pointed in a correct order.
It is of course possible to set various function other than those described above such as a function for allowing the emergence pattern (display positions), color, shape, size and background color of the targets and dummy targets to change, by appropriately selecting the data stored in the data base and control program in the image control device.